Estimating hazard ratios from published Kaplan‐Meier survival curves: A methods validation study
Bibliographic record
Abstract
OBJECTIVE: Various statistical methods have been developed to estimate hazard ratios (HRs) from published Kaplan-Meier (KM) curves for the purpose of performing meta-analyses. The objective of this study was to determine the reliability, accuracy, and precision of four commonly used methods by Guyot, Williamson, Parmar, and Hoyle and Henley. DESIGN: Pivotal randomized controlled trials (RCTs) in oncology were identified from the pan-Canadian Oncology Drug Review (pCODR) database (primary analysis) and the Food and Drug Administration's (FDA) drug approvals page (secondary analysis) between January 2012 and May 2016. Two reviewers independently reconstructed HRs using each method on KM curves extracted from each trial and compared them with reported HRs (gold standard). Bland-Altman plots and summary statistics were calculated to assess accuracy and precision of these methods. Interrater reliability was assessed using intraclass correlation coefficient (ICC). These four methods were also applied to KM curves of different structures (ie, flat versus steep curves). RESULTS: A total of 118 KM curves (55 RCTs) and 77 KM curves (46 RCTs) were extracted from pCODR and FDA, respectively. In the primary analysis, the Guyot method was the most accurate with the lowest mean error (0.0094; 95% CI, -0.0012-0.020). All four methods had excellent interrater reliability. The Guyot method showed the smallest bias and greatest precision on the Bland-Altman plots. The Guyot method was consistently superior in both the secondary and all sensitivity analyses. CONCLUSION: In the absence of reported HRs, we recommend that researchers consider the Guyot method to reconstruct HRs from KM curves when performing aggregate data meta-analyses.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.471 | 0.742 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.003 | 0.011 |
| Bibliometrics | 0.009 | 0.009 |
| Science and technology studies | 0.002 | 0.003 |
| Scholarly communication | 0.004 | 0.004 |
| Open science | 0.004 | 0.004 |
| Research integrity | 0.002 | 0.003 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; the direct Gemma label and the distilled Codex classifier agree on what is shown here.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".